Lith-type photographic material

ABSTRACT

THE JOINT USE OF CERTAIN PYRAZOLONE COMPOUNDS TOGETHER WITH A GOLD SENSITIZER IS FOUND TO BE PARTICULARLY EFFECTIVE TO OBTAIN A LITH-TYPE SILVER HALIDE PHOTOGRAPHIC EMULSION IMPROVED IN HIGH-INTENSITY RECIPROCITY FAILURE. THE PYRAZOLONE COMPOUND HAS THE GENERAL FORMULA:   1-(X-PHENYL),3-R-PYRAZOLIN-5-ONE   WHERE R IS AN ACYLAMINO, ARYLAMINO, ALYL, ARYL OR ARALKYL GROUP AND X IS A HYDROGEN ATOM, HALOGEN ATOM, CARBOXYL, SULFONE, PHENOXY AMINO OR NITRO GROUP.

July 20, 1971 TSUNEQ SUGA ETAL 3,594,173

LITE-TYPE PHOTOGRAPHIG MATERIAL Filed Oct. 30, 1968LOGAzQ/T/M/OFEXPUSURE AMOU/VTQ //V (MS LOGAR/Tfi/M 0F EXPOSURE 77/1454SECOND United States Patent US. Cl. 96-108 3 Claims ABSTRACT OF THEDISCLOSURE The joint use of certain pyrazolone compounds together with agold sensitizer is found to be particularly efiective to obtain alith-type silver halide photographic emulsion improved in high-intensityreciprocity failure. The pyrazolone compound has the general formula:

wherein R is an acylamino, arylamino, alkyl, aryl or aralkyl group and Xis a hydrogen atom, halogen atom, carboxyl, sulfone, phenoxy amino ornitro group.

This invention relates to a light-sensitive silver halide photographicmaterial. More particularly, the present invention is concerned with alight-sensitive silver halide photographic material useful for halftonereproduction (this is referred to as a lith-type film hereafter). It isan object of the invention to provide a lith-type film which is improvedin high-intensity reciprocity failure.

As a general rule, the amount of exposure when a lightsensitivephotographic material is subjected to exposure can be expressed as theproduct of light intensity and exposure time. Accordingly, if the lightintensity as great as ten times of its original intensity is used, theexposure time can be decreased to one-tenth its original time thereby toobtain the original result. Usual photo-snapping is conducted accordingto the above relationship by adjusting a diaphragm value and an exposuretime. However, when light intensity is extremely large or small, thedeviation of photographic characteristics occurs even at the sameexposure amount. For example, the decrease in photographic speed isobserved when exposure at high intensities for a short exposure time orat low intensities for a long exposure time is made. This phenomenon iswell known as reciprocity law failure.

A lith-type fil-m also sutfers from the above phenomenon. Further,lith-type film is usually required to be treated with an infectiousdeveloper having a low sulfite ion concentration and containinghydroquinone, because high image contrast and sharp halftone dots aredesired. If the lith-type film is treated with the infectious developer,much more reciprocity law failure occurs in comparison with thetreatment with a usual developer (metholhydroquinone). Particularly,reciprocity law failure is severe at high intensities. For example, whenexposure is conducted at a gradually decreased exposure time of 10, 10-10- 10 10 and 1() seconds at the correspondingly gradually increasedintensities, the image density of photographs obtained by the samedevelopment remarkably decreases.

Patented July 20,, 1971 As is known, a flask light source having anexposure time as short as 10- seconds has been adopted in the graphicart in view of the improvement in operative efficiency. Thus, alith-type film suited for light exposure at high intensities for a shortexposure time is very useful in the current graphic art.

The present invention provides a lith-type fil-m suited for the objectsindicated hereinbefore.

The present invention is related to a light-sensitive silver halidephotographic material of the lith-type, characterized by that apyrazolone compound of the general formula (wherein R represents anacylamino, arylamino, alkyl, aryl or aralkyl group and X represents ahydrogen atom, halogen atom, carboxyl, sulfone, phenoxy, amino or nitrogroup) and a gold sensitizer are incorporated in the emulsion layer or alayer adjacent thereto.

Typical pyrazolone compounds of the above general formula are listedbelow:

SOaH

The pyrazolone compounds used in this invention are not limited to thosegiven above.

As gold compounds, the following compounds are used:

In addition, all 'of gold compounds used as gold sensitizers forordinary light-sensitive silver halide photographic materials are alsoeffective in this invention.

Single use of each of the compounds in this invention is veryinsufiicient to decrease high-intensity reciprocity failure resultingfrom infectious development.

This invention is based on the observation that, as evidentlyillustrated in the examples below, reciprocity laW failure at highintensities is significantly improved 'by jointly incorporating both ofthe above compounds. 7

The amount of these compounds is variable according to the classbelonging to and preferable amount of the pyrazolone compound is from 5mg. to 10 g. per mol of silver halide and the gold compound ispreferably used in an amount of 0.1-100 mg. calculated on the basis ofgold atom per mol of silver halide. These compounds may be dissolved inany suitable solvent such as water, alkali, methanol, etc. and be addedat any stage of silver halide 1 formation, ripening and pre-coating.Alternatively, these compounds can be added to a layer adjacent to theemulsion layer, such as protective layer or inter layer as well asemulsion layer.

The compounds of the present invention are applicable.

- to the photographic emulsion which has been sensitized by EXAMPLE 1 Toa silver chlorobromide emulsion containing 20 mol percent of silverbromide was added each compound indicated in the Table 1 below. Eachemulsion was subjected to ripening at 55 C. for 60 minutes andthereafter added With chrome alum as a hardening agent and saponin as acoating aid. The resulting emulsion was applied onto a support anddried. Each sample thus obtained was exposed to light through astepwedge for 10, l* 10 10 10' and 10* seconds with a definite amount ofexposure and then treated-with an infectious developer having thefollowing composition:

Warrned water: 500 cc.

Addition product of formaldehyde and sodium sulfite:

Hydroquinone: 19 g.

Sodium carbonate: 80 g.

Boric acid: g.

Potassium bromide: 2 g.

Water to make up to 1000 cc.

The treatment with the above infectious developer was carried out at 20C. for 3 minutes. The amounts of exposure required for obtaining 1.0 ofthe density at each of the above exposure times were determined andplotted to give the reciprocity law curve as shown in the attacheddrawing was formulated. In the drawing, the solid line indicates thereciprocity law curve obtained with the sample (1), the dotted lineobtained with the sample (2), the single dot chain line obtained withthe sample (3) and the double dot chain line obtained with the sample(4).

TABLE 1 Compounds of this invention Pyrazolone compound No. (3) 0.14 g.

As obvious from the drawing, the lith-type film of this invention(corresponding to the sample 4) is remarkably improved in high-intensityreciprocity failure.

EXAMPLE 2 The same silver halide emulsion as used in the Example 1 wasadded with the compounds indicated in the Table 2 below and subjected tothe ripening. Thereafter, a coating aid (e..g. saponin) and an opticalsensitizing dye (e.g. merocyanine) were added to the emulsion which wasthen applied onto a support and dried. After being exposed to light for10- and 10 seconds, each sample was treated with the same developer asused in the Example 1 at 20 C. for 3 minutes. An amount of exposurerequired for obtaining 1.0 of the density was determined and the ratioof said amount at the exposure time of 10'- and 10 seconds wascalculated.

lone compound No. (9), 0.16 g.

The result obtained evidently indicates that high-intensity reciprocityfailure is markedly decreased in the llth-type material according tothis invention.

EXAMPLE 3 To the same silver halide emulsion as used in the Example 1was added 0.6 mg. of the gold compound (listed as No. (1)) per mol ofsilver halide. The resulting emulsion was subjected to ripening andadded With a hardening agent and coating aid. This emulsion was coatedon a film base. Then, the emulsion layer was further coated with a 1.5%gelatine solution containing 0.7 g. of the pyrazolone compound (given asNo. (4)) per 1 kg. of the solution to form a protective layer. Ascompared with a photographic material comprising a protective layer inwhich such pyrazolone compound was not incorporated, the lith-type filmhaving the protective layer formed as above was remarkably improved inhighintensity reciprocity failure.

What we claim is:

1. A light-sensitive silver halide non-color-photographic material ofthe lith-type, which comprises a support and supported thereon, alight-sensitive silver halide emulsion layer having a pyrazolonecompound of the general formula H (i1-("JR wherein R is an acylamino,arylamino, alkyl, aryl or aralkyl group and X is a hydrogen atom,halogen atom, carboxyl, sulfone, phenoxy, nitro or amino group and agold sensitizer for ordinary light-sensitive silver halide photographicmaterials incorporated in the said emulsion layer or a layer adjacentthereto.

2. A light-sensitive silver halide photographic material of thelith-type as calimed in claim 1, wherein said pyrazolone compound isincorporated in an amount of 0.005- 10 g. per mol of the silver halide.

3. A light-sensitive silver halide photographic material of thelith-type as claimed in claim 1, said gold sensitizer is incorporated inan amount of 0.1- mg. per mol of the silver halide.

References Cited UNITED STATES PATENTS 2,213,986 9/1940 Kendall 96-5652,343,703 3/1944 Porter 96-565 2,803,544 8/1957 Greenhalgh 96-742,933,391 4/1960 Feniak et a1. 96-56.5 3,079,255 2/ 1963 Wahl et al.96-56.5 3,127,269 3/1964 Greenhalgh et al 96--56.5 3,128,185 4/1964Goffe 96108 3,152,896 10/ 1964 Tuite 96--56.5 3,503,749 3/ 1970Tavernier 96-108 WILLIAM D. MARTIN, Primary Examiner R. M. SPEER,Assistant Examiner US. Cl. X.R. 96107

